Machine for producing screwthreads



Dec. 14, 194s. A ,GREEN 2,456,407

MACHINE FOR PRODIAJGING SCREWTHREADS Original Filed June 14, 1944 \NVENTOR jig/fw ATTO RN EY Patented Dec. 14, 1948 MACHINE FOR PRODUCING SCREWTHREADS Arthur Green, Coventry, England Original application June 14, 1944, Serial'No. 540,285, now Patent No. 2,403,075, .dated` July I 2, 1946. Divided and this-application Septem- Y ber 25, 1945, Serial No.' 618,553.11 Britain April 14, 1943 -In Great 3 claims. (c1. sic-irez) ,l

Section 1, Public Law 690, August 8, 1946 v Patent expires December 23, 1963 This invention relates to machines for producing screwthreads of the kind having an element for supporting rotatably the work upon which the screwthread is to be produced, a driving member, for transmitting power to the machine, means for imparting rotary movement from said driving member to said work, an element adapted to support a tool vfor forming the screwthread, said` two elements being relatively reciprocable in a direction substantially along the axis of the thread to be formed, means for imparting reciprocating movement from said driving member to one of said two elements, and means inter-connecting said two movements so that the pitch of the thread to be formed may thereby be controlledy being a division of Patent No. 2,403,075, granted July 2, 1946.

With machines of the above kind, inthe case of an ordinary parallel thread, the two elements would be reciprocated relatively in a direction which was parallel to the axis of the ,thread to be formed, but in the case of a taper thread they kwould be reciprocated relatively in a direction which was only substantially parallel to the axis of the thread to be formed, i. e. in a direction substantially along such axis, there being a slight angle of inclination between the axis of the thread to be formed and the direction of relative reciprocation of the two elements. y Furthermore, in such machines, the reciprocating movement is sometimes imparted to the tool supporting element, or sometimes to the work element, or sometimes both elements are displaced so as to produce a relative reciprocation.

In such machines it is a commonpractice to drive the rotating work and the reciprocating element from the same driving shaft, the drive being transmitted by gearing to the work rotating member and by gear, which may take the form of a leading screw and nut, to produce' the reciprocating movement. i The mechanism forming the subject of this invention is not necessarily a complete machine for producing screwthreads, but may be an at-` tachment adapted to be fitted to an existing machine having the necessary facilities for fitting and having a thread-producing tool.

The primary object of the present invention is to provide a new or improved form of mechanism for producing the movement of the reciprocating element,

Another object of the invention is to provide such mechanism which can conveniently be fitted as an attachment to an existing machine; A

Other objects ofthe invention will become apparent from the following description and accompanying drawings, wherein:

Figure 1 is a plan view showing a machine constructed in'a'ccordance with the present invention.

Figure 2 isa View in side elevation.

In the construction illustrated, the machine comprises astationary main support I0 which at one side "carries a'thread-producing or nishing tool indicated diagrammatically at II. This too1"maybe fof' any known `form7 `and may, for instance, comprisea rotary wheel having one or l more annular ribs for cutting or grinding the thread, or the tool may consist of a non-rotary member shaped for forming the thread groove. Mounted on the upperv surface ofthe support I0 so that it can reciprocate thereover in guides in the direction indicatedfby the arrows shown in Figure 2, is the reciprocating element I2 which may be inthe form of a table of known construction and may be mounted on the lsupport in any known manner. i f

One end of the reciprocating element I2 carries a tail-stock indicated at I 3 for supporting one end ofthe work Ill, and the opposite end of the reciprocating element isprovided with a block I5 incorporating a bearing I6 for a shaft 53 carrying a head vstock 24 for supporting the other end of the work, and having means 54 for driving the Work through the medium of a lathe dog 25.

Mounted on the sideof the block I5 is a casing 55 provided with a bearing 56 for a cross driving shaft I'I which may be power-driven or may be driven by a hand wheel I8. The driving shaft I1 is provided with aworm 5l engaging a worm wheel 58on the shaft 53, the worm and worm wheel being located within the casing 55. Rotation of the shaft-ll drives the shaft 53, and the shaft 53` projects from one end of the casing 55 and is provided withva `rotary disc 23 having two grooves 59, in which operate two flexible bands ywhich extend around the disc 23 in opposite di- -rections, andwhich have end'portions 35 connectedto a transverse slide 43.

The rotary disc 23 is thus mounted upon an axis which is parallel to the'direction of movement of the reciprocating element I2 and the flexible bands have the endportions 35 connected to a transverse slide 43 extending at right angles to the direction of reciprocation which transverse slide acts in the manner of a wedge between the reciprocating element and an inclined abutment 44 mounted upon the stationary support I0.

Conveniently, the transverse slide is provided with van inclined surface member 45 which is angularly adjustable in relation to the slide by providing the member 45 with an arcuate slot 46 through which extends an adjusting bolt 41, and this surface part is provided, at the endopposite to the slot, with a groove 48 into which extends the adjacent part of the abutment 44 while the latter is angularly adjustable in relation to the support IIl by fastening it thereto through the medium of an adjusting screw 49 For supporting the transverse slide in relation to the element I2 it is provided With a dove-tail or T section rib 50 at theside opposite to the abutment which engages in"a `groove 5I` of similar section shaped in the adjacent end'rof the recip-A rocating element, the rib and-groove extending at right angles to the direction of reciprocation.

With such an arrangement when drive is imparted to the shaft I1 so that the work I4 and disc 23 are rotated in the manner already described the slide 43 is moved transversely to the the surface part and the inclined abutment 44 as by slackening the screws 41, 49. As ra result the machine can ,s readily be adjusted to suit threads of different pitch.

The endwise displacement of the reciprocating element is produced by the inclined abutment 44 engaged by the inclined side 45 and the slide. The action is that of a wedge and it is immaterial whether the inclined surfaceis on the slide or on the abutment or on the end of the reciprocating element.r Further the inclined surface may lengage orbe engaged by a similarly inclined surface or by a roller or other abutment. It is obviously desirable that the angle of inclination of the inclined surface shall be capable of adjustment.

A machine constructed in accordance with the present invention possesses the great advantage that by imparting the necessary movement to the reciprocating elementY from the rotary disc through the medium of one or more exible bands in the manner described, lost or irregular motion between the relatively moving members is reduced to a minimum as compared With an arrangement in whichv the movement is transmitted by means of a lead screw or rack andpinion gearing so that the machine possesses a high degree of accuracy. Y

Although I have described a construction in which the reciprocating element carries the work and the thread producing tool is stationary it Yshould be understood that it is Within the scope of my invention that the thread x.producing tool could be mounted upon a reciprocating element so that it reciprocates therewith and the work merely rotates.

What I claim then is:

l. A machine for producing screwthreads comprising an element for rotatably supporting the work upon which the screwthread is to be prof ,duced at both ends, means for rotating said work,

4 tably on said Work supporting element with its plane transverse to the direction of reciprocation vof said Work supporting element 'and adapted to reciprocatetherewith, means for imparting rotary movement to said disc, a slide member mounted .in a rectilinear guide on said Work supporting element for reciprocatic-n thereon in a direction transverse to the direction of reciprocation of said work supporting element and parallel to the plane of the disc, abutments mounted on said slide member and said tool support, said abutments having interengaging faces adapted for relative 'sliding movement disposed at an inclination to the direction of relative reciprccation oi said two elements and to the direction of reciprocation of the slide member, said abutments being adjustable relative to the slide member and work support to vary therangle of inclination of said interengaging abutment faces with respect to the said directions of reciprocation, a pair of iiexible bands arranged side by side and engaging the periphery of the disc, one end of each 0f said bandsA being secured to the disc, the other end of each of said bands being secured to the slide member with the said other ends extending in opposite directions with respect to each other and substantially parallel to the direction of reciprocation of said slide member the interengaging' faces on said abutments producing lateral movement ofthe slide which is directly transmitted to the work supporting element by pressure onthe rectilinear guide.

2'. A machine for producing screwthreads comprising an element having means for rotatably supporting the Work upon which the screwthread is to be produced at both ends, an element adapted to support a tool for forming the screwthread, said Work supporting element being mounted on saidtool supporting element for reciprocatory movement relative thereto in a direction substantially along the axis of the thread to be formed, a gear casing mounted on one end of said work supporting element, an intermediate shaft mounted rotatably in said gear casing, extending substantially parallel to the direction of reciprocation of said Work supporting element, means for imparting rotary movement to said intermediate shaft, one end of said intermediate shaft being adapted to impart vrotation to said Work, a disc mounted on the other end of said intermediate shaft with its plane transverse to said shaft and to the direction of reciprocation of said work supporting element, aslide member mounted on said work supporting element for reciprocation thereon in a direction transverse to the direction of reciprocation of said work supporting element and parallel to the plane of the disc, abutments mounted on said slide member and said tool support, said abutments having interengaging faces adapted for relative sliding movement, said abutments being adjustable relative to the slide member and work supportto vary the angle of inclinationof said interengaging abutment faces with respect to the said directions of reciprocation, a pair of flexible bands arranged side by side and engaging the periphery of the disc, one end of each of said bands being secured to the disc, the other end of each of said bands being secured to the slide member with the said other ends extending in opposite directions with respect to each other, and substantially parallel to the direction of reciprocation of said slide member whereby in operation movement of the slide produces an end thrust on the Work supporting element causing 5 it to move parallel to the axis of the intermediate shaft.

3. A machine for producing screwthreads comprising a main support having at onel side a thread producing or iinishing tool, guides on the main support, a reciprocating element in said guides, a tail stock on said reciprocating element for supporting one end of the Work, a block on said element, said block being spaced from the tail stock, a bearing in said block, a'headstock shaft in said bearing, a headstock carried by said shaft and supporting the opposite end of the work, means associated with said shaft for driving the work, a casing mounted on the side of said block, a bearing in said casing, a cross driving shaft in said bearing, gearing in said casing connecting the cross driving shaft to the headstock shaft, said headstock shaft extending through and project-v ing from the side of said casing, a disc secured on the projecting part 0f the headstock shaft, two

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,791,424 Metzler Feb. 3, 1931 2,375,052 Umbdenstock May 1, 1945 2,378,302 Kline June 12, 1945 

